A washing machine comprises: an outer tub containing water; an inner tub rotating on a vertical axis within the outer tub and having a first opening at the bottom; a motor providing torque; a dewatering shaft rotating by the motor; and a hub supporting the inner tub from the bottom, wherein the hub comprises: a connecting boss whose center is connected to the dewatering shaft; a plurality of spokes extending outward radially from the connecting boss and having second openings overlapping the first opening; and a circular flange connecting the outer edges of the spokes and attached to the bottom of the inner tub, wherein the spokes comprise at least one first spoke whose underside faces the bottom of the outer tub and is entirely smooth.